I'm not a fan of motherboard RAID as it's annoying to set up the OS with, and at least from what I saw enabling RAID mode adds a few seconds to boot time (BIOS takes longer to show you the RAID config). Since you're already used to managing more than 1 drive letter (by your My System Specs having 3 drives), I'd do something like high-spec 128GB SSD for OS/small apps, 256GB low-end SSD for games that are I/O bound, and mechanical drives for everything else. Note however an SSD will only help games that stutter due to not pre-caching textures/models, like MMO games.

__________________"The computer programmer says they should drive the car around the block and see if the tire fixes itself." [src]